[linux-block.git] / net / core / xdp.c

// SPDX-License-Identifier: GPL-2.0-only
/* net/core/xdp.c
 *
 * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
 */
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/rhashtable.h>
#include <linux/bug.h>
#include <net/page_pool.h>

#include <net/xdp.h>
#include <net/xdp_priv.h> /* struct xdp_mem_allocator */
#include <trace/events/xdp.h>
#include <net/xdp_sock_drv.h>

#define REG_STATE_NEW		0x0
#define REG_STATE_REGISTERED	0x1
#define REG_STATE_UNREGISTERED	0x2
#define REG_STATE_UNUSED	0x3

static DEFINE_IDA(mem_id_pool);
static DEFINE_MUTEX(mem_id_lock);
#define MEM_ID_MAX 0xFFFE
#define MEM_ID_MIN 1
static int mem_id_next = MEM_ID_MIN;

static bool mem_id_init; /* false */
static struct rhashtable *mem_id_ht;

static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
{
	const u32 *k = data;
	const u32 key = *k;

	BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
		     != sizeof(u32));

	/* Use cyclic increasing ID as direct hash key */
	return key;
}

static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
			  const void *ptr)
{
	const struct xdp_mem_allocator *xa = ptr;
	u32 mem_id = *(u32 *)arg->key;

	return xa->mem.id != mem_id;
}

static const struct rhashtable_params mem_id_rht_params = {
	.nelem_hint = 64,
	.head_offset = offsetof(struct xdp_mem_allocator, node),
	.key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
	.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
	.max_size = MEM_ID_MAX,
	.min_size = 8,
	.automatic_shrinking = true,
	.hashfn    = xdp_mem_id_hashfn,
	.obj_cmpfn = xdp_mem_id_cmp,
};

static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
{
	struct xdp_mem_allocator *xa;

	xa = container_of(rcu, struct xdp_mem_allocator, rcu);

	/* Allow this ID to be reused */
	ida_simple_remove(&mem_id_pool, xa->mem.id);

	kfree(xa);
}

static void mem_xa_remove(struct xdp_mem_allocator *xa)
{
	trace_mem_disconnect(xa);

	if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
		call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
}

static void mem_allocator_disconnect(void *allocator)
{
	struct xdp_mem_allocator *xa;
	struct rhashtable_iter iter;

	mutex_lock(&mem_id_lock);

	rhashtable_walk_enter(mem_id_ht, &iter);
	do {
		rhashtable_walk_start(&iter);

		while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
			if (xa->allocator == allocator)
				mem_xa_remove(xa);
		}

		rhashtable_walk_stop(&iter);

	} while (xa == ERR_PTR(-EAGAIN));
	rhashtable_walk_exit(&iter);

	mutex_unlock(&mem_id_lock);
}

void xdp_unreg_mem_model(struct xdp_mem_info *mem)
{
	struct xdp_mem_allocator *xa;
	int type = mem->type;
	int id = mem->id;

	/* Reset mem info to defaults */
	mem->id = 0;
	mem->type = 0;

	if (id == 0)
		return;

	if (type == MEM_TYPE_PAGE_POOL) {
		rcu_read_lock();
		xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
		page_pool_destroy(xa->page_pool);
		rcu_read_unlock();
	}
}
EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);

void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
{
	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
		WARN(1, "Missing register, driver bug");
		return;
	}

	xdp_unreg_mem_model(&xdp_rxq->mem);
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);

void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
{
	/* Simplify driver cleanup code paths, allow unreg "unused" */
	if (xdp_rxq->reg_state == REG_STATE_UNUSED)
		return;

	xdp_rxq_info_unreg_mem_model(xdp_rxq);

	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
	xdp_rxq->dev = NULL;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);

static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
{
	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
}

/* Returns 0 on success, negative on failure */
int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
		     struct net_device *dev, u32 queue_index, unsigned int napi_id)
{
	if (!dev) {
		WARN(1, "Missing net_device from driver");
		return -ENODEV;
	}

	if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
		WARN(1, "Driver promised not to register this");
		return -EINVAL;
	}

	if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
		WARN(1, "Missing unregister, handled but fix driver");
		xdp_rxq_info_unreg(xdp_rxq);
	}

	/* State either UNREGISTERED or NEW */
	xdp_rxq_info_init(xdp_rxq);
	xdp_rxq->dev = dev;
	xdp_rxq->queue_index = queue_index;
	xdp_rxq->napi_id = napi_id;

	xdp_rxq->reg_state = REG_STATE_REGISTERED;
	return 0;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);

void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
{
	xdp_rxq->reg_state = REG_STATE_UNUSED;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);

bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
{
	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);

static int __mem_id_init_hash_table(void)
{
	struct rhashtable *rht;
	int ret;

	if (unlikely(mem_id_init))
		return 0;

	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
	if (!rht)
		return -ENOMEM;

	ret = rhashtable_init(rht, &mem_id_rht_params);
	if (ret < 0) {
		kfree(rht);
		return ret;
	}
	mem_id_ht = rht;
	smp_mb(); /* mutex lock should provide enough pairing */
	mem_id_init = true;

	return 0;
}

/* Allocate a cyclic ID that maps to allocator pointer.
 * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
 *
 * Caller must lock mem_id_lock.
 */
static int __mem_id_cyclic_get(gfp_t gfp)
{
	int retries = 1;
	int id;

again:
	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
	if (id < 0) {
		if (id == -ENOSPC) {
			/* Cyclic allocator, reset next id */
			if (retries--) {
				mem_id_next = MEM_ID_MIN;
				goto again;
			}
		}
		return id; /* errno */
	}
	mem_id_next = id + 1;

	return id;
}

static bool __is_supported_mem_type(enum xdp_mem_type type)
{
	if (type == MEM_TYPE_PAGE_POOL)
		return is_page_pool_compiled_in();

	if (type >= MEM_TYPE_MAX)
		return false;

	return true;
}

static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
						     enum xdp_mem_type type,
						     void *allocator)
{
	struct xdp_mem_allocator *xdp_alloc;
	gfp_t gfp = GFP_KERNEL;
	int id, errno, ret;
	void *ptr;

	if (!__is_supported_mem_type(type))
		return ERR_PTR(-EOPNOTSUPP);

	mem->type = type;

	if (!allocator) {
		if (type == MEM_TYPE_PAGE_POOL)
			return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
		return NULL;
	}

	/* Delay init of rhashtable to save memory if feature isn't used */
	if (!mem_id_init) {
		mutex_lock(&mem_id_lock);
		ret = __mem_id_init_hash_table();
		mutex_unlock(&mem_id_lock);
		if (ret < 0) {
			WARN_ON(1);
			return ERR_PTR(ret);
		}
	}

	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
	if (!xdp_alloc)
		return ERR_PTR(-ENOMEM);

	mutex_lock(&mem_id_lock);
	id = __mem_id_cyclic_get(gfp);
	if (id < 0) {
		errno = id;
		goto err;
	}
	mem->id = id;
	xdp_alloc->mem = *mem;
	xdp_alloc->allocator = allocator;

	/* Insert allocator into ID lookup table */
	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
	if (IS_ERR(ptr)) {
		ida_simple_remove(&mem_id_pool, mem->id);
		mem->id = 0;
		errno = PTR_ERR(ptr);
		goto err;
	}

	if (type == MEM_TYPE_PAGE_POOL)
		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect, mem);

	mutex_unlock(&mem_id_lock);

	return xdp_alloc;
err:
	mutex_unlock(&mem_id_lock);
	kfree(xdp_alloc);
	return ERR_PTR(errno);
}

int xdp_reg_mem_model(struct xdp_mem_info *mem,
		      enum xdp_mem_type type, void *allocator)
{
	struct xdp_mem_allocator *xdp_alloc;

	xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
	if (IS_ERR(xdp_alloc))
		return PTR_ERR(xdp_alloc);
	return 0;
}
EXPORT_SYMBOL_GPL(xdp_reg_mem_model);

int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
			       enum xdp_mem_type type, void *allocator)
{
	struct xdp_mem_allocator *xdp_alloc;

	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
		WARN(1, "Missing register, driver bug");
		return -EFAULT;
	}

	xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
	if (IS_ERR(xdp_alloc))
		return PTR_ERR(xdp_alloc);

	trace_mem_connect(xdp_alloc, xdp_rxq);
	return 0;
}

EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);

/* XDP RX runs under NAPI protection, and in different delivery error
 * scenarios (e.g. queue full), it is possible to return the xdp_frame
 * while still leveraging this protection.  The @napi_direct boolean
 * is used for those calls sites.  Thus, allowing for faster recycling
 * of xdp_frames/pages in those cases.
 */
static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
			 struct xdp_buff *xdp)
{
	struct xdp_mem_allocator *xa;
	struct page *page;

	switch (mem->type) {
	case MEM_TYPE_PAGE_POOL:
		rcu_read_lock();
		/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
		page = virt_to_head_page(data);
		if (napi_direct && xdp_return_frame_no_direct())
			napi_direct = false;
		page_pool_put_full_page(xa->page_pool, page, napi_direct);
		rcu_read_unlock();
		break;
	case MEM_TYPE_PAGE_SHARED:
		page_frag_free(data);
		break;
	case MEM_TYPE_PAGE_ORDER0:
		page = virt_to_page(data); /* Assumes order0 page*/
		put_page(page);
		break;
	case MEM_TYPE_XSK_BUFF_POOL:
		/* NB! Only valid from an xdp_buff! */
		xsk_buff_free(xdp);
		break;
	default:
		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
		WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
		break;
	}
}

void xdp_return_frame(struct xdp_frame *xdpf)
{
	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
}
EXPORT_SYMBOL_GPL(xdp_return_frame);

void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
{
	__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
}
EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);

/* XDP bulk APIs introduce a defer/flush mechanism to return
 * pages belonging to the same xdp_mem_allocator object
 * (identified via the mem.id field) in bulk to optimize
 * I-cache and D-cache.
 * The bulk queue size is set to 16 to be aligned to how
 * XDP_REDIRECT bulking works. The bulk is flushed when
 * it is full or when mem.id changes.
 * xdp_frame_bulk is usually stored/allocated on the function
 * call-stack to avoid locking penalties.
 */
void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
{
	struct xdp_mem_allocator *xa = bq->xa;

	if (unlikely(!xa || !bq->count))
		return;

	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
	bq->count = 0;
}
EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);

/* Must be called with rcu_read_lock held */
void xdp_return_frame_bulk(struct xdp_frame *xdpf,
			   struct xdp_frame_bulk *bq)
{
	struct xdp_mem_info *mem = &xdpf->mem;
	struct xdp_mem_allocator *xa;

	if (mem->type != MEM_TYPE_PAGE_POOL) {
		__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
		return;
	}

	xa = bq->xa;
	if (unlikely(!xa)) {
		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
		bq->count = 0;
		bq->xa = xa;
	}

	if (bq->count == XDP_BULK_QUEUE_SIZE)
		xdp_flush_frame_bulk(bq);

	if (unlikely(mem->id != xa->mem.id)) {
		xdp_flush_frame_bulk(bq);
		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	}

	bq->q[bq->count++] = xdpf->data;
}
EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);

void xdp_return_buff(struct xdp_buff *xdp)
{
	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
}

/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
{
	struct xdp_mem_allocator *xa;
	struct page *page;

	rcu_read_lock();
	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	page = virt_to_head_page(data);
	if (xa)
		page_pool_release_page(xa->page_pool, page);
	rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(__xdp_release_frame);

void xdp_attachment_setup(struct xdp_attachment_info *info,
			  struct netdev_bpf *bpf)
{
	if (info->prog)
		bpf_prog_put(info->prog);
	info->prog = bpf->prog;
	info->flags = bpf->flags;
}
EXPORT_SYMBOL_GPL(xdp_attachment_setup);

struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
{
	unsigned int metasize, totsize;
	void *addr, *data_to_copy;
	struct xdp_frame *xdpf;
	struct page *page;

	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
	metasize = xdp_data_meta_unsupported(xdp) ? 0 :
		   xdp->data - xdp->data_meta;
	totsize = xdp->data_end - xdp->data + metasize;

	if (sizeof(*xdpf) + totsize > PAGE_SIZE)
		return NULL;

	page = dev_alloc_page();
	if (!page)
		return NULL;

	addr = page_to_virt(page);
	xdpf = addr;
	memset(xdpf, 0, sizeof(*xdpf));

	addr += sizeof(*xdpf);
	data_to_copy = metasize ? xdp->data_meta : xdp->data;
	memcpy(addr, data_to_copy, totsize);

	xdpf->data = addr + metasize;
	xdpf->len = totsize - metasize;
	xdpf->headroom = 0;
	xdpf->metasize = metasize;
	xdpf->frame_sz = PAGE_SIZE;
	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;

	xsk_buff_free(xdp);
	return xdpf;
}
EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);

/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
void xdp_warn(const char *msg, const char *func, const int line)
{
	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
};
EXPORT_SYMBOL_GPL(xdp_warn);

int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
{
	n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
				      n_skb, skbs);
	if (unlikely(!n_skb))
		return -ENOMEM;

	return 0;
}
EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);

struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
					   struct sk_buff *skb,
					   struct net_device *dev)
{
	unsigned int headroom, frame_size;
	void *hard_start;

	/* Part of headroom was reserved to xdpf */
	headroom = sizeof(*xdpf) + xdpf->headroom;

	/* Memory size backing xdp_frame data already have reserved
	 * room for build_skb to place skb_shared_info in tailroom.
	 */
	frame_size = xdpf->frame_sz;

	hard_start = xdpf->data - headroom;
	skb = build_skb_around(skb, hard_start, frame_size);
	if (unlikely(!skb))
		return NULL;

	skb_reserve(skb, headroom);
	__skb_put(skb, xdpf->len);
	if (xdpf->metasize)
		skb_metadata_set(skb, xdpf->metasize);

	/* Essential SKB info: protocol and skb->dev */
	skb->protocol = eth_type_trans(skb, dev);

	/* Optional SKB info, currently missing:
	 * - HW checksum info		(skb->ip_summed)
	 * - HW RX hash			(skb_set_hash)
	 * - RX ring dev queue index	(skb_record_rx_queue)
	 */

	/* Until page_pool get SKB return path, release DMA here */
	xdp_release_frame(xdpf);

	/* Allow SKB to reuse area used by xdp_frame */
	xdp_scrub_frame(xdpf);

	return skb;
}
EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);

struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
					 struct net_device *dev)
{
	struct sk_buff *skb;

	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
	if (unlikely(!skb))
		return NULL;

	memset(skb, 0, offsetof(struct sk_buff, tail));

	return __xdp_build_skb_from_frame(xdpf, skb, dev);
}
EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);

struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf)
{
	unsigned int headroom, totalsize;
	struct xdp_frame *nxdpf;
	struct page *page;
	void *addr;

	headroom = xdpf->headroom + sizeof(*xdpf);
	totalsize = headroom + xdpf->len;

	if (unlikely(totalsize > PAGE_SIZE))
		return NULL;
	page = dev_alloc_page();
	if (!page)
		return NULL;
	addr = page_to_virt(page);

	memcpy(addr, xdpf, totalsize);

	nxdpf = addr;
	nxdpf->data = addr + headroom;
	nxdpf->frame_sz = PAGE_SIZE;
	nxdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
	nxdpf->mem.id = 0;

	return nxdpf;
}
Commit	Line	Data
ddc64d0a	1	// SPDX-License-Identifier: GPL-2.0-only
aecd67b6 JDB	2	/* net/core/xdp.c
	3	*
	4	* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
aecd67b6	5	*/
05296620 JK	6	#include <linux/bpf.h>
05296620 JK	7	#include <linux/filter.h>
aecd67b6 JDB	8	#include <linux/types.h>
aecd67b6 JDB	9	#include <linux/mm.h>
05296620	10	#include <linux/netdevice.h>
8d5d8852 JDB	11	#include <linux/slab.h>
	12	#include <linux/idr.h>
	13	#include <linux/rhashtable.h>
34cc0b33	14	#include <linux/bug.h>
57d0a1c1	15	#include <net/page_pool.h>
aecd67b6 JDB	16
aecd67b6 JDB	17	#include <net/xdp.h>
f033b688 JDB	18	#include <net/xdp_priv.h> /* struct xdp_mem_allocator */
f033b688 JDB	19	#include <trace/events/xdp.h>
2b43470a	20	#include <net/xdp_sock_drv.h>
aecd67b6 JDB	21
	22	#define REG_STATE_NEW 0x0
	23	#define REG_STATE_REGISTERED 0x1
	24	#define REG_STATE_UNREGISTERED 0x2
	25	#define REG_STATE_UNUSED 0x3
	26
8d5d8852 JDB	27	static DEFINE_IDA(mem_id_pool);
	28	static DEFINE_MUTEX(mem_id_lock);
	29	#define MEM_ID_MAX 0xFFFE
	30	#define MEM_ID_MIN 1
	31	static int mem_id_next = MEM_ID_MIN;
	32
	33	static bool mem_id_init; /* false */
	34	static struct rhashtable *mem_id_ht;
	35
8d5d8852 JDB	36	static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
	37	{
	38	const u32 *k = data;
	39	const u32 key = *k;
	40
c593642c	41	BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
8d5d8852 JDB	42	!= sizeof(u32));
8d5d8852 JDB	43
9f9a7077 N	44	/* Use cyclic increasing ID as direct hash key */
9f9a7077 N	45	return key;
8d5d8852 JDB	46	}
	47
	48	static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
	49	const void *ptr)
	50	{
	51	const struct xdp_mem_allocator *xa = ptr;
	52	u32 mem_id = (u32 )arg->key;
	53
	54	return xa->mem.id != mem_id;
	55	}
	56
	57	static const struct rhashtable_params mem_id_rht_params = {
	58	.nelem_hint = 64,
	59	.head_offset = offsetof(struct xdp_mem_allocator, node),
	60	.key_offset = offsetof(struct xdp_mem_allocator, mem.id),
c593642c	61	.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
8d5d8852 JDB	62	.max_size = MEM_ID_MAX,
	63	.min_size = 8,
	64	.automatic_shrinking = true,
	65	.hashfn = xdp_mem_id_hashfn,
	66	.obj_cmpfn = xdp_mem_id_cmp,
	67	};
	68
	69	static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
	70	{
	71	struct xdp_mem_allocator *xa;
	72
	73	xa = container_of(rcu, struct xdp_mem_allocator, rcu);
	74
	75	/* Allow this ID to be reused */
	76	ida_simple_remove(&mem_id_pool, xa->mem.id);
	77
8d5d8852 JDB	78	kfree(xa);
	79	}
	80
c3f812ce	81	static void mem_xa_remove(struct xdp_mem_allocator *xa)
99c07c43	82	{
c3f812ce	83	trace_mem_disconnect(xa);
99c07c43	84
c3f812ce	85	if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
99c07c43	86	call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
99c07c43 JDB	87	}
99c07c43 JDB	88
c3f812ce JL	89	static void mem_allocator_disconnect(void *allocator)
	90	{
	91	struct xdp_mem_allocator *xa;
	92	struct rhashtable_iter iter;
	93
86c76c09 JL	94	mutex_lock(&mem_id_lock);
86c76c09 JL	95
c3f812ce JL	96	rhashtable_walk_enter(mem_id_ht, &iter);
	97	do {
	98	rhashtable_walk_start(&iter);
	99
	100	while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
	101	if (xa->allocator == allocator)
	102	mem_xa_remove(xa);
	103	}
	104
	105	rhashtable_walk_stop(&iter);
99c07c43	106
c3f812ce JL	107	} while (xa == ERR_PTR(-EAGAIN));
c3f812ce JL	108	rhashtable_walk_exit(&iter);
86c76c09 JL	109
86c76c09 JL	110	mutex_unlock(&mem_id_lock);
c3f812ce JL	111	}
c3f812ce JL	112
4a48ef70	113	void xdp_unreg_mem_model(struct xdp_mem_info *mem)
8d5d8852 JDB	114	{
8d5d8852 JDB	115	struct xdp_mem_allocator *xa;
4a48ef70 THJ	116	int type = mem->type;
4a48ef70 THJ	117	int id = mem->id;
8d5d8852	118
a78cae24	119	/* Reset mem info to defaults */
4a48ef70 THJ	120	mem->id = 0;
4a48ef70 THJ	121	mem->type = 0;
dce5bd61	122
8d5d8852 JDB	123	if (id == 0)
	124	return;
	125
a78cae24	126	if (type == MEM_TYPE_PAGE_POOL) {
c3f812ce JL	127	rcu_read_lock();
	128	xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
	129	page_pool_destroy(xa->page_pool);
	130	rcu_read_unlock();
99c07c43	131	}
8d5d8852	132	}
4a48ef70 THJ	133	EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);
	134
	135	void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
	136	{
	137	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
	138	WARN(1, "Missing register, driver bug");
	139	return;
	140	}
	141
	142	xdp_unreg_mem_model(&xdp_rxq->mem);
	143	}
dce5bd61	144	EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
8d5d8852	145
aecd67b6 JDB	146	void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
	147	{
	148	/* Simplify driver cleanup code paths, allow unreg "unused" */
	149	if (xdp_rxq->reg_state == REG_STATE_UNUSED)
	150	return;
	151
dce5bd61	152	xdp_rxq_info_unreg_mem_model(xdp_rxq);
8d5d8852	153
aecd67b6 JDB	154	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
	155	xdp_rxq->dev = NULL;
	156	}
	157	EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
	158
	159	static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
	160	{
	161	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
	162	}
	163
	164	/* Returns 0 on success, negative on failure */
	165	int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
b02e5a0e	166	struct net_device *dev, u32 queue_index, unsigned int napi_id)
aecd67b6	167	{
f85b244e YD	168	if (!dev) {
	169	WARN(1, "Missing net_device from driver");
	170	return -ENODEV;
	171	}
	172
aecd67b6 JDB	173	if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
	174	WARN(1, "Driver promised not to register this");
	175	return -EINVAL;
	176	}
	177
	178	if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
	179	WARN(1, "Missing unregister, handled but fix driver");
	180	xdp_rxq_info_unreg(xdp_rxq);
	181	}
	182
aecd67b6 JDB	183	/* State either UNREGISTERED or NEW */
	184	xdp_rxq_info_init(xdp_rxq);
	185	xdp_rxq->dev = dev;
	186	xdp_rxq->queue_index = queue_index;
b02e5a0e	187	xdp_rxq->napi_id = napi_id;
aecd67b6 JDB	188
	189	xdp_rxq->reg_state = REG_STATE_REGISTERED;
	190	return 0;
	191	}
	192	EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
	193
	194	void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
	195	{
	196	xdp_rxq->reg_state = REG_STATE_UNUSED;
	197	}
	198	EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
c0124f32 JDB	199
	200	bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
	201	{
	202	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
	203	}
	204	EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
5ab073ff	205
8d5d8852 JDB	206	static int __mem_id_init_hash_table(void)
	207	{
	208	struct rhashtable *rht;
	209	int ret;
	210
	211	if (unlikely(mem_id_init))
	212	return 0;
	213
	214	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
	215	if (!rht)
	216	return -ENOMEM;
	217
	218	ret = rhashtable_init(rht, &mem_id_rht_params);
	219	if (ret < 0) {
	220	kfree(rht);
	221	return ret;
	222	}
	223	mem_id_ht = rht;
	224	smp_mb(); /* mutex lock should provide enough pairing */
	225	mem_id_init = true;
	226
	227	return 0;
	228	}
	229
	230	/* Allocate a cyclic ID that maps to allocator pointer.
	231	* See: https://www.kernel.org/doc/html/latest/core-api/idr.html
	232	*
	233	* Caller must lock mem_id_lock.
	234	*/
	235	static int __mem_id_cyclic_get(gfp_t gfp)
	236	{
	237	int retries = 1;
	238	int id;
	239
	240	again:
	241	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
	242	if (id < 0) {
	243	if (id == -ENOSPC) {
	244	/* Cyclic allocator, reset next id */
	245	if (retries--) {
	246	mem_id_next = MEM_ID_MIN;
	247	goto again;
	248	}
	249	}
	250	return id; /* errno */
	251	}
	252	mem_id_next = id + 1;
	253
	254	return id;
	255	}
	256
57d0a1c1 JDB	257	static bool __is_supported_mem_type(enum xdp_mem_type type)
	258	{
	259	if (type == MEM_TYPE_PAGE_POOL)
	260	return is_page_pool_compiled_in();
	261
	262	if (type >= MEM_TYPE_MAX)
	263	return false;
	264
	265	return true;
	266	}
	267
4a48ef70 THJ	268	static struct xdp_mem_allocator __xdp_reg_mem_model(struct xdp_mem_info mem,
	269	enum xdp_mem_type type,
	270	void *allocator)
5ab073ff	271	{
8d5d8852 JDB	272	struct xdp_mem_allocator *xdp_alloc;
	273	gfp_t gfp = GFP_KERNEL;
	274	int id, errno, ret;
	275	void *ptr;
	276
57d0a1c1	277	if (!__is_supported_mem_type(type))
4a48ef70	278	return ERR_PTR(-EOPNOTSUPP);
5ab073ff	279
4a48ef70	280	mem->type = type;
5ab073ff	281
57d0a1c1	282	if (!allocator) {
0807892e	283	if (type == MEM_TYPE_PAGE_POOL)
4a48ef70 THJ	284	return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
4a48ef70 THJ	285	return NULL;
57d0a1c1	286	}
8d5d8852 JDB	287
	288	/* Delay init of rhashtable to save memory if feature isn't used */
	289	if (!mem_id_init) {
	290	mutex_lock(&mem_id_lock);
	291	ret = __mem_id_init_hash_table();
	292	mutex_unlock(&mem_id_lock);
	293	if (ret < 0) {
	294	WARN_ON(1);
4a48ef70	295	return ERR_PTR(ret);
8d5d8852 JDB	296	}
	297	}
	298
	299	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
	300	if (!xdp_alloc)
4a48ef70	301	return ERR_PTR(-ENOMEM);
8d5d8852 JDB	302
	303	mutex_lock(&mem_id_lock);
	304	id = __mem_id_cyclic_get(gfp);
	305	if (id < 0) {
	306	errno = id;
	307	goto err;
	308	}
4a48ef70 THJ	309	mem->id = id;
4a48ef70 THJ	310	xdp_alloc->mem = *mem;
8d5d8852 JDB	311	xdp_alloc->allocator = allocator;
	312
	313	/* Insert allocator into ID lookup table */
	314	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
	315	if (IS_ERR(ptr)) {
4a48ef70 THJ	316	ida_simple_remove(&mem_id_pool, mem->id);
4a48ef70 THJ	317	mem->id = 0;
8d5d8852 JDB	318	errno = PTR_ERR(ptr);
	319	goto err;
	320	}
	321
1da4bbef	322	if (type == MEM_TYPE_PAGE_POOL)
64693ec7	323	page_pool_use_xdp_mem(allocator, mem_allocator_disconnect, mem);
1da4bbef	324
8d5d8852	325	mutex_unlock(&mem_id_lock);
5ab073ff	326
4a48ef70	327	return xdp_alloc;
8d5d8852 JDB	328	err:
	329	mutex_unlock(&mem_id_lock);
	330	kfree(xdp_alloc);
4a48ef70 THJ	331	return ERR_PTR(errno);
	332	}
	333
	334	int xdp_reg_mem_model(struct xdp_mem_info *mem,
	335	enum xdp_mem_type type, void *allocator)
	336	{
	337	struct xdp_mem_allocator *xdp_alloc;
	338
	339	xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
	340	if (IS_ERR(xdp_alloc))
	341	return PTR_ERR(xdp_alloc);
	342	return 0;
	343	}
	344	EXPORT_SYMBOL_GPL(xdp_reg_mem_model);
	345
	346	int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
	347	enum xdp_mem_type type, void *allocator)
	348	{
	349	struct xdp_mem_allocator *xdp_alloc;
	350
	351	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
	352	WARN(1, "Missing register, driver bug");
	353	return -EFAULT;
	354	}
	355
	356	xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
	357	if (IS_ERR(xdp_alloc))
	358	return PTR_ERR(xdp_alloc);
	359
	360	trace_mem_connect(xdp_alloc, xdp_rxq);
	361	return 0;
5ab073ff	362	}
4a48ef70	363
5ab073ff	364	EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
8d5d8852	365
389ab7f0 JDB	366	/* XDP RX runs under NAPI protection, and in different delivery error
389ab7f0 JDB	367	* scenarios (e.g. queue full), it is possible to return the xdp_frame
baead859	368	* while still leveraging this protection. The @napi_direct boolean
389ab7f0	369	* is used for those calls sites. Thus, allowing for faster recycling
ed1182dc	370	* of xdp_frames/pages in those cases.
389ab7f0	371	*/
ed1182dc BT	372	static void __xdp_return(void data, struct xdp_mem_info mem, bool napi_direct,
ed1182dc BT	373	struct xdp_buff *xdp)
8d5d8852	374	{
57d0a1c1 JDB	375	struct xdp_mem_allocator *xa;
	376	struct page *page;
	377
	378	switch (mem->type) {
	379	case MEM_TYPE_PAGE_POOL:
	380	rcu_read_lock();
	381	/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
	382	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	383	page = virt_to_head_page(data);
622d1369 OBL	384	if (napi_direct && xdp_return_frame_no_direct())
622d1369 OBL	385	napi_direct = false;
458de8a9	386	page_pool_put_full_page(xa->page_pool, page, napi_direct);
57d0a1c1 JDB	387	rcu_read_unlock();
	388	break;
	389	case MEM_TYPE_PAGE_SHARED:
8d5d8852	390	page_frag_free(data);
57d0a1c1 JDB	391	break;
	392	case MEM_TYPE_PAGE_ORDER0:
	393	page = virt_to_page(data); /* Assumes order0 page*/
8d5d8852	394	put_page(page);
57d0a1c1	395	break;
ed1182dc BT	396	case MEM_TYPE_XSK_BUFF_POOL:
	397	/* NB! Only valid from an xdp_buff! */
	398	xsk_buff_free(xdp);
	399	break;
57d0a1c1 JDB	400	default:
57d0a1c1 JDB	401	/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
82c41671	402	WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
57d0a1c1	403	break;
8d5d8852 JDB	404	}
8d5d8852 JDB	405	}
c497176c BT	406
	407	void xdp_return_frame(struct xdp_frame *xdpf)
	408	{
ed1182dc	409	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
c497176c	410	}
8d5d8852	411	EXPORT_SYMBOL_GPL(xdp_return_frame);
c497176c	412
389ab7f0 JDB	413	void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
389ab7f0 JDB	414	{
ed1182dc	415	__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
389ab7f0 JDB	416	}
	417	EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
	418
89653987 LB	419	/* XDP bulk APIs introduce a defer/flush mechanism to return
	420	* pages belonging to the same xdp_mem_allocator object
	421	* (identified via the mem.id field) in bulk to optimize
	422	* I-cache and D-cache.
	423	* The bulk queue size is set to 16 to be aligned to how
	424	* XDP_REDIRECT bulking works. The bulk is flushed when
	425	* it is full or when mem.id changes.
	426	* xdp_frame_bulk is usually stored/allocated on the function
	427	* call-stack to avoid locking penalties.
	428	*/
	429	void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
	430	{
	431	struct xdp_mem_allocator *xa = bq->xa;
89653987	432
78862447	433	if (unlikely(!xa \|\| !bq->count))
89653987 LB	434	return;
89653987 LB	435
78862447	436	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
89653987 LB	437	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
	438	bq->count = 0;
	439	}
	440	EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
	441
	442	/* Must be called with rcu_read_lock held */
	443	void xdp_return_frame_bulk(struct xdp_frame *xdpf,
	444	struct xdp_frame_bulk *bq)
	445	{
	446	struct xdp_mem_info *mem = &xdpf->mem;
	447	struct xdp_mem_allocator *xa;
	448
	449	if (mem->type != MEM_TYPE_PAGE_POOL) {
46d5e62d	450	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
89653987 LB	451	return;
	452	}
	453
	454	xa = bq->xa;
	455	if (unlikely(!xa)) {
	456	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	457	bq->count = 0;
	458	bq->xa = xa;
	459	}
	460
	461	if (bq->count == XDP_BULK_QUEUE_SIZE)
	462	xdp_flush_frame_bulk(bq);
	463
	464	if (unlikely(mem->id != xa->mem.id)) {
	465	xdp_flush_frame_bulk(bq);
	466	bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	467	}
	468
	469	bq->q[bq->count++] = xdpf->data;
	470	}
	471	EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
	472
c497176c BT	473	void xdp_return_buff(struct xdp_buff *xdp)
c497176c BT	474	{
ed1182dc	475	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
c497176c	476	}
05296620	477
6bf071bf JDB	478	/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
	479	void __xdp_release_frame(void data, struct xdp_mem_info mem)
	480	{
	481	struct xdp_mem_allocator *xa;
	482	struct page *page;
	483
	484	rcu_read_lock();
	485	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	486	page = virt_to_head_page(data);
	487	if (xa)
	488	page_pool_release_page(xa->page_pool, page);
	489	rcu_read_unlock();
	490	}
	491	EXPORT_SYMBOL_GPL(__xdp_release_frame);
	492
05296620 JK	493	void xdp_attachment_setup(struct xdp_attachment_info *info,
	494	struct netdev_bpf *bpf)
	495	{
	496	if (info->prog)
	497	bpf_prog_put(info->prog);
	498	info->prog = bpf->prog;
	499	info->flags = bpf->flags;
	500	}
	501	EXPORT_SYMBOL_GPL(xdp_attachment_setup);
b0d1beef BT	502
	503	struct xdp_frame xdp_convert_zc_to_xdp_frame(struct xdp_buff xdp)
	504	{
72962167	505	unsigned int metasize, totsize;
b0d1beef BT	506	void addr, data_to_copy;
	507	struct xdp_frame *xdpf;
	508	struct page *page;
	509
	510	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
	511	metasize = xdp_data_meta_unsupported(xdp) ? 0 :
	512	xdp->data - xdp->data_meta;
b0d1beef BT	513	totsize = xdp->data_end - xdp->data + metasize;
	514
	515	if (sizeof(*xdpf) + totsize > PAGE_SIZE)
	516	return NULL;
	517
	518	page = dev_alloc_page();
	519	if (!page)
	520	return NULL;
	521
	522	addr = page_to_virt(page);
	523	xdpf = addr;
	524	memset(xdpf, 0, sizeof(*xdpf));
	525
	526	addr += sizeof(*xdpf);
	527	data_to_copy = metasize ? xdp->data_meta : xdp->data;
	528	memcpy(addr, data_to_copy, totsize);
	529
	530	xdpf->data = addr + metasize;
	531	xdpf->len = totsize - metasize;
	532	xdpf->headroom = 0;
	533	xdpf->metasize = metasize;
3ff23516	534	xdpf->frame_sz = PAGE_SIZE;
b0d1beef BT	535	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
b0d1beef BT	536
82c41671	537	xsk_buff_free(xdp);
b0d1beef BT	538	return xdpf;
	539	}
	540	EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);
34cc0b33 JDB	541
	542	/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
	543	void xdp_warn(const char msg, const char func, const int line)
	544	{
	545	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
	546	};
	547	EXPORT_SYMBOL_GPL(xdp_warn);
97a0e1ea	548
65e6dcf7 LB	549	int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
	550	{
	551	n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
	552	n_skb, skbs);
	553	if (unlikely(!n_skb))
	554	return -ENOMEM;
	555
	556	return 0;
	557	}
	558	EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);
	559
97a0e1ea LB	560	struct sk_buff __xdp_build_skb_from_frame(struct xdp_frame xdpf,
	561	struct sk_buff *skb,
	562	struct net_device *dev)
	563	{
	564	unsigned int headroom, frame_size;
	565	void *hard_start;
	566
	567	/* Part of headroom was reserved to xdpf */
	568	headroom = sizeof(*xdpf) + xdpf->headroom;
	569
	570	/* Memory size backing xdp_frame data already have reserved
	571	* room for build_skb to place skb_shared_info in tailroom.
	572	*/
	573	frame_size = xdpf->frame_sz;
	574
	575	hard_start = xdpf->data - headroom;
	576	skb = build_skb_around(skb, hard_start, frame_size);
	577	if (unlikely(!skb))
	578	return NULL;
	579
	580	skb_reserve(skb, headroom);
	581	__skb_put(skb, xdpf->len);
	582	if (xdpf->metasize)
	583	skb_metadata_set(skb, xdpf->metasize);
	584
	585	/* Essential SKB info: protocol and skb->dev */
	586	skb->protocol = eth_type_trans(skb, dev);
	587
	588	/* Optional SKB info, currently missing:
	589	* - HW checksum info (skb->ip_summed)
	590	* - HW RX hash (skb_set_hash)
	591	* - RX ring dev queue index (skb_record_rx_queue)
	592	*/
	593
	594	/* Until page_pool get SKB return path, release DMA here */
	595	xdp_release_frame(xdpf);
	596
	597	/* Allow SKB to reuse area used by xdp_frame */
	598	xdp_scrub_frame(xdpf);
	599
	600	return skb;
	601	}
	602	EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);
89f479f0 LB	603
	604	struct sk_buff xdp_build_skb_from_frame(struct xdp_frame xdpf,
	605	struct net_device *dev)
	606	{
	607	struct sk_buff *skb;
	608
	609	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
	610	if (unlikely(!skb))
	611	return NULL;
	612
	613	memset(skb, 0, offsetof(struct sk_buff, tail));
	614
	615	return __xdp_build_skb_from_frame(xdpf, skb, dev);
	616	}
	617	EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
e624d4ed HL	618
	619	struct xdp_frame xdpf_clone(struct xdp_frame xdpf)
	620	{
	621	unsigned int headroom, totalsize;
	622	struct xdp_frame *nxdpf;
	623	struct page *page;
	624	void *addr;
	625
	626	headroom = xdpf->headroom + sizeof(*xdpf);
	627	totalsize = headroom + xdpf->len;
	628
	629	if (unlikely(totalsize > PAGE_SIZE))
	630	return NULL;
	631	page = dev_alloc_page();
	632	if (!page)
	633	return NULL;
	634	addr = page_to_virt(page);
	635
	636	memcpy(addr, xdpf, totalsize);
	637
	638	nxdpf = addr;
	639	nxdpf->data = addr + headroom;
	640	nxdpf->frame_sz = PAGE_SIZE;
	641	nxdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
	642	nxdpf->mem.id = 0;
	643
	644	return nxdpf;
	645	}